This invention relates to water saving toilet flush tanks, and more particularly to a variable flush control apparatus which is readily adapted for installation in a conventional flush tank to provide for easy adjustment of the level or levels at which the tank discharge valve will reseat to limit the quantity of water discharged during each flush.
Conventional flush tanks now in general use discharge the entire amount of water stored in the tank upon each flushing operation even though only a fraction of that quantity of water may be required for flushing the waste material. This results in unnecessary water consumption, increased water costs and presents special problems where the water is flushed into a cesspool or septic tank. In many places there is a critical shortage of water, and this waste contributes significantly to the shortage. In addition, many municipal waste disposal systems are already overburdened with the increasing quantities of sewerage water that flows through the sewer systems and treatment plants.
It has long been recognized that substantial water saving can be achieved by the provision of a variable flushing control for varying the quantity of water utilized in flushing in accordance with the quantity and character of the waste material to be flushed. Toward this end, various water saving flush tanks and variable flushing control devices have been proposed in the past.
One type of flush tank heretofore proposed includes a partitioned tank, separate water discharging devices and duplication of plumbing for discharging water from one or both parts of the partitioned tank. In another type, the discharge of water from the tank is controlled by two columns in end-to-end relationship with provision for lifting the upper column for a partial flush and both columns for a full flush.
Other types of variable flushing control devices have been proposed which rely on the venting of air from the conventional hollow ball valve to effect a partial flush. For example, in the variable flushing control device described in the Christie et al U.S. Pat. No. 2,741,776, a tube supporting a ball-type discharge valve has a positively actuated valve at the upper end thereof to partially exhaust air from an air chamber within the ball valve when the ball valve is lifted to bring the valve into contact with an actuating bar. The partial evacuation of the air from the ball valve permits gradual reseating of the ball valve upon release thereof. A number of other systems using the venting principle have been devised, but in general, these prior art proposals employ complicated and expensive structures and are not adapted for use in conventional flush tanks.